World population is predicted to reach 10 billion people by the year 2050, increasing more than 75% over the current population. Development of new contraceptive options is necessary to provide accessible birth control to all individuals regardless of sociological, financial, or educational limitations. Current literature implicates marketed spermicidal formulations in cervical and vaginal irritation leading to lesions and acquisition of sexually transmitted diseases. Reassessment of these spermicides by the FDA may result in increased costs or their removal from the market. New, inexpensive spermicides with improved safety and effectiveness must be developed. The objective of this research proposal is the development of a spermicide based on an anti-sperm monoclonal antibody, S19. This mAb inhibits human sperm function and gamete interactions in vitro. The proposed Phase l study will test the feasibility of expressing and purifying sufficient quantities of biologically active recombinant S19 antibody. Towards the expression of a recombinant S19 antibody, the S19 heavy and light chain variable regions were cloned and sequenced. The specific aims of this research proposal are to express recombinant S19 antibody and evaluate the antigen-binding activity of the recombinant antibody. The proposed research will provide a model for anti-sperm antibody immunocontraceptives. PROPOSED COMMERCIAL APPLICATIONS The S19 mAb inhibits human sperm function and gamete interactions and is therefore an attractive candidate for the development of an antibody-based, intravaginal spermicide. The proposed studies will examine recombinant S19 ScFv to determine its feasibility as an inexpensive source of the S19 antibody.